By analyzing drinking-water samples from U.S. treatment plants, a multi-institute research team has identified some unexpected by-products of disinfection processes. The data indicate compounds that toxicologists should target for further study, the researchers say.
Reactions between disinfection chemicals, such as chlorine and ozone, and natural organic matter in water create a wide variety of by-products. Primarily through laboratory studies, researchers have identified more than 500 of these disinfection by-products.
The Environmental Protection Agency regulates a handful of the by-products, including trihalomethanes (THMs), that have been shown to be toxic to animals and are prevalent in U.S. water systems.
For the new study, the team tested water from 12 treatment plants for the 50 unregulated by-products that EPA scientists ranked as most likely to cause cancer. To increase the likelihood of finding these by-products, Stuart W. Krasner of the Metropolitan Wa